Hierarchical Control Strategy for Active Suspension Equipped with an Electromagnetic Actuator

Electromagnetic suspension systems have increasingly gained widespread attention due to their superiority in improving ride comfort while providing fast response, excellent controllability and high mechanical efficiency, but their applications are limited due to the accuracy of the underlying control actuation tracking. For addressing this problem, this study presents a novel hierarchical control strategy for an electromagnetic active suspension (EMAS) system equipped with an electromagnetic actuator (EMA) structure. The structure of the EMA device and the working principle of the motion conversion model are introduced in detail first, and the motion conversion equation is derived based on the force-torque relationship. Based on this, a linear quadratic regulator (LQR) control method is proposed to be applied to a half-vehicle suspension system to improve the vibration isolation performance of the vehicle and ensure the ride comfort. Then, the underlying layer control of the permanent magnet synchronous motor (PMSM) based on field-oriented control (FOC) is adopted to tracking the active control forces generated by the upper LQR controller. Immediately afterwards, the EMA converts the torque generated by the motor into vertical forces acting on the suspension through rational synergies between the upper LQR controller and the underlying motor controller, which ultimately achieves active control of the vehicle suspension system. The simulations are carried out from the perspective of the half-vehicle integrated with the EMA, which demonstrate that the proposed EMAS system has greatly reduced vehicle vertical and pitch accelerations compared to the conventional passive suspension, significantly improving the ride comfort and vibration isolation effect on external excitation.